Biomass of fine roots in different land cover types at the "arc of deforestation", Brazil

This study aims to evaluate the effect of land cover type, soil properties, and vegetation structure on fine root biomass, and examined how these factors affect diameter of fine roots. The study was conducted in communities located in the Nova Ipixuna, Parauapebas and Pacajá municipalities of Pará state. In each area, nine farms were selected; in each farm were sampled five plots, totaling 135 plots distributed into nine different types of land cover; at each plot, four soil samples were collected to quantify the fine roots, vegetation cover was inventoried, and soil was collected for physical and chemical characterization. Fine roots were separated into four different classes. Principal Component Analysis (PCA) were done for the soil and vegetation matrix and they were compared with the fine root biomass PCA through a co-inertia analysis. Variability was high for fine root biomass data. All land covers exhibited a high proportion of fine roots > 1 mm. The co- inertia analysis showed that the fine root biomass PCA share a common structure with vegetation PCA, with 37/100 of the variability being explained; however only 9/100 of the variability was explained by the soil PCA. Our results highlight the importance of roots with diameters 2 mm was critical to the differentiation among land covers

Successional processes in agricultural mosaics in the eastern Amazon

Most tropical landscapes are mainly composed of dynamic mosaics involving multiple land uses. Different histories of land use management can lead to different successional paths. The aim of this study was to determine if there is a successional floristic gradient related to land use types and how these gradients change across three rural mosaics in Eastern Amazon. We also investigated what are the indicator species across mosaics and land use types and how they change through succession. Five sampling points were established in nine family farms at each mosaic. A detrended correspondence analysis was used to reveal the successional gradient. A multivariate regression tree was used to analyze differences in floristic composition between mosaics and land uses. Floristic similarity between land uses formed successional gradient at the mosaics, in which agricultural land uses represent the early stages of secondary succession and forests represent more advanced stages. Total number of species and total number of shade-tolerant species were correlated with advanced successional stages in all mosaics, but pioneer trees were also correlated with advanced stages in fragmented mosaics. Each mosaic had a distinct successional series due to different management approaches. Where the matrix was mainly composed of forest fragments and the human intervention period was shorter, land use types were more similar to one another as they were grouped into fewer successional stages. Thus, the floristic similarity between land use types appears as an indicator of successional advancement across the mosaics and help determine the regenerative capacity of those areas

Riqueza de plantas em mosaicos rurais na região do "arco do desmatamento", Amazônia Oriental, Brasil

A variação da riqueza de espécies entre diferentes mosaicos rurais e tipos de uso da terra foi analisada em escala local e da paisagem. Nove tipos de uso entre três mosaicos rurais foram comparados através de curvas de rarefação estabelecidas para três estratos verticais da vegetação. A riqueza foi fortemente influenciada pela composição dos tipos de uso implantados em cada fazenda na paisagem. Florestas secundárias tiveram maior riqueza em mosaicos com maior cobertura florestal de alta riqueza na paisagem

Riqueza de plantas em mosaicos rurais na região do "arco do desmatamento", Amazônia Oriental, Brasil

A variação da riqueza de espécies entre diferentes mosaicos rurais e tipos de uso da terra foi analisada em escala local e da paisagem. Nove tipos de uso entre três mosaicos rurais foram comparados através de curvas de rarefação estabelecidas para três estratos verticais da vegetação. A riqueza foi fortemente influenciada pela composição dos tipos de uso implantados em cada fazenda na paisagem. Florestas secundárias tiveram maior riqueza em mosaicos com maior cobertura florestal de alta riqueza na paisagem

Substituição do milho por palma forrageira em dietas completas para vacas em lactação Replacement of corn by forage cactus in the total mixed rations for crossbreed lactating cows

Objetivou-se, com este experimento, avaliar o efeito da substituição do milho por palma forrageira sobre o desempenho de vacas mestiças em lactação e a digestibilidade dos nutrientes. Foram utilizadas oito vacas mestiças (5/8 HZ), distribuídas em dois quadrados latinos 4 x 4 em esquema fatorial 2 x 2 (duas cultivares de palma forrageira, com ou sem milho). Não houve interação entre palma e milho e o efeito dos dois alimentos foi analisado de forma isolada. Os consumos de matéria seca, de fibra em detergente ácido, dematéria orgânica, de proteína bruta, de extrato etéreo e de carboidratos totais não foram influenciados pelas cultivares de palma utilizadas. Animais que receberam palma gigante nas dietas apresentaram maior consumo de fibra em detergente neutro. As dietas com milho proporcionaram maior consumo de matéria seca (kg/dia e % de PV). O consumo de NDT, os coeficientes de digestibilidade de todos os nutrientes, a produção de leite corrigida, o teor de gordura e a eficiência alimentar não foram influenciados pelas cultivares de palma forrageira ou pela inclusão milho.<br>The experiment was conduced to evaluate the effects of corn replacement for forage cactus on the performance of crossbreed lactating cows and nutrient digestibility. Eight cows were assigned a two latin square design in a factorial 2 x 2 arrangement (two forage cactus cultivars, with or without corn).There was not interaction between forage cactus and corn and the effect of both were analyzed in an isolated way. The intake of dry matter, organic matter, acid detergent fiber, crude protein, ether extract and total carbohydrates were not affected by the forage cactus. Animals that received giant cultivar presented larger neutral detergent fiber intake. The diets with corn presented larger dry matter intake (kg/day and % of LW). The intake of TDN, the coefficients of digestibility of all nutrients, the fat corrected milk production, fat content and kg of milk: dry matter intake ratio were not affected not by the forage cactus cultivars neither by the inclusion of corn

Multi-messenger Observations of a Binary Neutron Star Merger

International audienceOn 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of $\sim 1.7\,{\rm{s}}$ with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg(2) at a luminosity distance of ${40}_{-8}^{+8}$ Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 $\,{M}_{\odot }$. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at $\sim 40\,{\rm{Mpc}}$) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ∼10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position $\sim 9$ and $\sim 16$ days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta